In electrophotography, also known as Xerography, electrophotographic imaging or electrostatographic imaging, the surface of an electrographic plate, drum, belt or the like (imaging member or photoreceptor) containing a photoconductive insulating layer on a conductive layer is first uniformly electrostatically charged. The imaging member is then exposed to a pattern of activating electromagnetic radiation, such as light. The radiation selectively dissipates the charge on the illuminated areas of the photoconductive insulating layer while leaving behind an electrostatic latent image on the non-illuminated areas. This electrostatic latent image may then be developed to form a visible image by depositing finely divided electroscopic marking particles on the surface of the photoconductive insulating layer. The resulting visible image may then be transferred from the imaging member directly or indirectly (such as by a transfer or other member) to a print substrate, such as transparency or paper. The imaging process may be repeated many times with reusable imaging members.
An electrophotographic imaging member may be provided in a number of forms. For example, the imaging member may be a homogenous layer of a single material vitreous selenium or it may be a composite layer containing a photoconductor and other materials. In addition, the imaging member may be layered in which each layer making up the member performs a certain function. Certain layered organic imaging members generally have at least a substrate layer and two electro or photoactive layers. These active layers generally include (1) a charge generating layer containing a light-absorbing material, and (2) a charge transport layer containing charge transport molecules or materials. These layers can be in a variety of orders to make up a functional device, and sometimes can be combined in a single or mixed layer. The substrate layer may be formed from a conductive material. Alternatively, a conductive layer can be formed on a non-conductive inert substrate by a technique such as but not limited to sputter coating.
The charge generating layer is capable of photo generating charge and injecting the photo generated charge into the charge transport layer or other layer.
In the charge transport layer, the charge transport molecules may be in a polymer binder. In this case, the charge transport molecules provide whole or electron transport properties, while the electrically inactive polymer binder provides mechanical properties. Alternatively, the charge transport layer can be made from a charge transporting polymer such as a vinyl polymer, polysilylene or polyether carbonate, wherein the charge transport properties are chemically incorporated into the mechanically robust polymer.
Imaging members may also include a charge blocking layer(s) and/or an adhesive layer(s) between the charge generating layer and the conductive substrate layer. In addition, imaging members may contain protective overcoatings. These protective overcoatings can be either electroactive or inactive, where electroactive overcoatings are generally preferred. Further, imaging members may include layers to provide special functions such as incoherent reflection of laser light, dot patterns and/or pictorial imaging or subbing layers to provide chemical sealing and/or a smooth coating surface.
Imaging members are generally exposed to repetitive electrophotographic cycling, which subjects the exposed charged transport layer or alternative top layer thereof to mechanical abrasion, chemical attack and heat. This repetitive cycling leads to gradual deterioration in the mechanical and electrical characteristics of the exposed charge transport layer.
Although excellent toner images may be obtained with multi-layered belt or drum photoreceptors, it has been found that as more advanced, higher speed electrophotographic copiers, duplicators, and printers are developed, there is a greater demand on print quality. The delicate balance in charging image and bias potentials, and characteristics of the toner and/or developer, must be maintained. This places additional constraints on the quality of photoreceptor manufacturing, and thus on the manufacturing yield.
Despite the various approaches that have been taken for forming imaging members there remains a need for improved imaging member design, to provide improved imaging performance, longer lifetime, and the like.
Song et al., A Cyclic Triphenylamine Dimer for Organic Field-Effect Transistors with High Performance, J. Arm. Chem. Soc., Vol. 128, No. 50, 2006, pages 15940-15941, describes the use of the below compound 1 for organic field-effect transistors (“OFETs”) with high mobility. Compound 1 was prepared in two steps from triphenylamine through the use of a Vilsmeier reaction followed by McMurry coupling (scheme 1). It was stated that this material has large solubility in common organic solvents such as dichloromethane, chloroform, and toluene. In the OFET devices, the hole mobility of one was found to be 1.5×10−2 cm2 V−1 s−1, which was a 100 times higher than the mobility of the below compound 2 under the same conditions.

